1. Field of the Invention
The present invention relates to a liquid discharge head for discharging liquid by bubble generation due to the action of heat energy on liquid, a head cartridge using the liquid discharge head, and a liquid discharge device. Further, the present invention relates to a new liquid discharge method including displacement of a movable member and bubble growth, a liquid discharge head, a head cartridge and a liquid discharge device for carrying out this liquid discharge method.
The present invention is an invention which can be applied to devices such as a printer which records on a recording medium, such as paper, thread, fiber, cloth, leather, metal, glass, ceramics and the like, a copy machine, a facsimile including a communication system, and a word processor including a printer section. Further the present invention can be applied to an industrial recording device compositely combined with each type of processing unit. A term "recording" means not only imparting an image having a meaning of a character and a figure or pattern etc., on a recording medium but also imparting an image having no meaning of the pattern etc., thereon.
2. Related Background Art
An ink jet recording process, so called a bubble jet recording process, in which a state change including a rapid volume change of ink (i.e., generation of bubbles) is caused to generate by imparting energy such as heat or the like to the ink, the ink is discharged from a discharge port by an active force due to this state change and the discharged ink is adhered to a medium to be recorded to perform an image formation, has been well known. In the recording device using this bubble jet recording process, as disclosed in publications of the specification of U.S. Pat. No. 4,723,129 and the like, there are generally provided a discharge port for discharging ink, an ink flow path communicated with this discharge port and an electrothermal converting member used as an energy generating means for discharging ink provided in the ink flow path.
According to such recording process, a high quality level image can be recorded at high speed and low noise and a discharge port for discharging ink can be provided at high density in a head in this recording process. Therefore, the recording process has a number of the advantages that a high revolution recording image and such color image could easily be obtained in a compact device. Thus, this bubble jet recording process has recently been used in various office equipment such as a printer, copy machine, facsimile and the like. Further, the recording process is used even in an industrial system such as a printing equipment etc.
With the increased use of the bubble jet technology in products in many fields, the following various demands are recently increased.
For example, an answer to demand of improvement of energy efficiency includes optimization of a heating element in which thickness of a protective film is controlled. This technology has an advantage in that the transmission efficiency of generated heat to liquid is enhanced.
Further, to obtain an extended definition image, there is provided a driving condition for imparting a liquid discharging method in which an improved ink discharge based on a stable bubble generation can be performed. Furthermore, to obtain a liquid discharge head having a high refilling speed of a discharged liquid to a liquid flow path from the viewpoint of the high speed recording, there is also provided a liquid discharge head having improved shapes of the liquid flow path.
A flow path structure and a head producing method disclosed in Japanese Patent Application Laid-Open No. 63-199972, relating to the shapes of the flow path, are patents that take notice of a back wave (pressure in a direction opposite to that toward a discharge port, that is pressure toward a liquid chamber) which is generated with the generation bubbles. This back wave is known as a loss energy since it is not an energy toward the discharge direction.
A head disclosed in the Japanese Patent Application Laid-Open No. 63-199972, has an ink jet head valve which is spaced from a bubbling area of bubbles formed by the heating element and is positioned at the opposite side to the discharge port with respect to the heating element. This valve has an initial position in a manner that it is adhered to the ceiling of the flow path by a head producing method using a plate material, and is hung down in the flow path with the generation of bubbles. This patent is disclosed as a patent in which an energy loss is controlled by controlling a part of the above-mentioned back wave with a valve.
However, in this configuration, as will be found by studying bubble behaviors in a liquid flow path just before and after bubble generation in the flow path supporting liquid to be discharged, suppression of a part of a back wave with a valve is not necessarily useful for discharging liquid. The back wave itself has no direct relation to the discharge of liquid by nature. Therefore, even though a part of the back wave was suppressed, the suppression does not impart a great influence to the discharge of liquid.